fix: pom.xml to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-ORGBOUNCYCASTLE-8731360

Author: snyk-bot

pom.xml

@@ -27,7 +27,7 @@
         <dependency>
             <groupId>org.web3j</groupId>
             <artifactId>core</artifactId>
-            <version>4.5.14</version>
+            <version>4.8.9-android</version>
         </dependency>
         <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-lang3 -->
         <dependency>